Project Summary/Abstract Head and neck squamous cell carcinoma (HNSCC) is the seventh most common cancer worldwide. Even with intensive surgery, radiotherapy and chemotherapy, the prognosis is still dismal. Completely removal (negative surgical margin) with surgery is the goal of the treatment, but it is difficult to achieve due to the infiltration of vital structures. Since positive surgery margin is associated with poor prognosis, there is a great need to develop novel treatments which could not only guide the surgery but also destroy the residual tumors while sparing normal tissues with important functions. Moreover, development of theranostic agents that can detect and eliminate early HNSCC lesions, particularly the aggressive sub-types, will have tremendous impact in many patients with HNSCC. We recently developed a set of highly innovative Transformable Nano- Theranostics (TNTs) that possess outstanding capability to circumvent the sequential biological barriers which have generally hindered drug delivery to tumors including HNSCC. We have demonstrated that 1) the smart dual size/charge- transformation of TNTs in response to tumor acidosis could dramatically increase the tumor accumulation and penetration of TNTs in HNSCC tissue, and facilitate uptake in cancer cells; 2) TNTs enabled effective visualization of tumor, drug delivery and therapeutic effect by magnetic resonance imaging (MRI) and near infrared fluorescence imaging (NIRFI); 3) the synergistic trimodal therapy via TNTs achieved a 100% complete cure rate in orthotopic HNSCC mouse models. These highly encouraging data suggest that such nano-platform can be translated into early detection and elimination of HNSCC lesions, which are readily accessible to illumination with light. The goal of this proposal is to tackle the biological barriers and translational barriers of theranostic agents via the development of highly effective, non-toxic yet easy-to-make targeting Transformable Nano-Theranostics (t-TNTs) for image-guided intervention using companion cats with spontaneous HNSCC. In aim 1, a robust set of t-TNT nanoconstructs with HNSCC targeting ligand will be developed, optimized and fully characterized. In aim 2, the biodistribution and tumor targeting properties of the selected t-TNTs will be studied with optical imaging and MRI in orthotopic HNSCC model. The in vivo toxicity and anti-tumor efficacy of the top t-TNTs will be evaluated in HNSCC xenograft models including PDX models. The best t-TNT nanoconstruct selected from aim 2 will be used for image-guided treatment studies in aim 3 in cats with spontaneous HNSCC. Successful development of such theranostic agents will significantly enhance the delivery of imaging agents and synergistic therapies of HNSCC while the therapeutic delivery process can be monitored at various spatial and temporal resolution scales. Results from this study will be significant not only in advancing the development of next-generation nano-theranostics for effective imaging & therapy of HNSCC, but also in generating new fundamental knowledge of using transformable nanotheranostics for overcoming a variety of biological barriers to enhance the efficiency of image-guided drug delivery in cancers.